Succinimides are both useful as drug and chemical precursors and are useful in the synthesis of molecular sieves, including zeolite catalysts. Succinimides may be readily reduced to amines and then converted to quaternary ammonium ions. Quaternary ammonium ions are typically used as the structure directing agents in zeolite catalysts. For example, zeolite MCM-68 may be made from quaternary ammonium ions as is described in U.S. Pat. No. 6,049,018. Other known zeolites that are typically produced using quaternary ammonium ions include SSZ-13, SSZ-15, SSZ-24, SSZ-31, and SSZ-37 as described in U.S. Pat. Nos. 5,281,407 and 5,641,393. It is important to discover new succinimides and more efficient methods of synthesis of succinimides to facilitate the discovery of new zeolites and the preparation of known zeolites.
Known processes for the preparation of succinimides include cyclisation of diols with amines, as described in WO 2012/002913 and by Zhang, J. et al., Angew. Chem. Int. Ed. 2010, 49, 6391-6395; and the reaction of succinic anhydrides with amines, as described in U.S. Pat. Nos. 5,554,768 and 4,847,069. Succinimides may also be produced from alkynes using iron carbonyl species, amines and copper chloride oxidation catalysts as described by Periasamy, M. et al. in J. Organomet. Chem. 2002, 649, 209-213.
A further process recently reported by Driller, K. M. et al., Angew. Chem. Int. Ed. 2009, 48, 6041-6044 and Chem. Eur. J. 2010, 16, 9606-9615 involves the reaction of an alkyne, carbon monoxide, and an amine in the presence of an iron catalyst. That process is an extremely efficient method to synthesize succinimides and has the advantage that the iron catalyst is innocuous and the advantage of being extremely flexible, allowing a wide range of substituent groups to be incorporated into the succinimides enabling the preparation of complex succinimide molecules, and hence complex quaternary ammonium ions for incorporation into zeolite catalysts, from small, readily available molecules. However, the process described by Driller, K. M. et al. (ibid.) is carried out in relatively high dilution in an ether solvent under an inert, i.e., air and water free, conditions and requires a large excess of amine over alkyne. For example, in the reaction of 270 mmol 3-hexyne (22 g) and cyclohexylamine to form 1-cyclohexyl-3,4-diethylpyrrolidine-2,5-dione, the method of Driller, K. M. et al. (ibid.) required air free, dry conditions, a 13 fold excess of amine, needed a 2 L reactor and produced a 56% yield of product. Thus, there remains a need for an improved method of synthesizing succinimides from alkyne starting materials, in particular, a need for an improved iron-catalyzed carbonylation process to prepare succinimides from alkynes and amines. There also remains a need for new structure directing agents for use in the synthesis of molecular sieves.
Molecular sieve materials, both natural and synthetic, have been demonstrated in the past to be useful as adsorbents and to have catalytic properties for various types of hydrocarbon conversion reactions. Certain molecular sieves, such as zeolites, AlPOs, and mesoporous materials, are ordered, porous crystalline materials having a definite crystalline structure as determined by X-ray diffraction (XRD). Within the crystalline molecular sieve material there are a large number of cavities which may be interconnected by a number of channels or pores. These cavities and pores are uniform in size within a specific molecular sieve material. Because the dimensions of these pores are such as to accept for adsorption molecules of certain dimensions while rejecting those of larger dimensions, these materials have come to be known as “molecular sieves” and are utilized in a variety of industrial processes.
Such molecular sieves, both natural and synthetic, include a wide variety of positive ion-containing crystalline silicates. These silicates can be described as rigid three-dimensional frameworks of SiO4 and Periodic Table Group 13 element oxide (e.g., AlO4). The tetrahedra are cross-linked by the sharing of oxygen atoms with the electrovalence of the tetrahedra containing the Group 13 element (e.g., aluminum or boron) being balanced by the inclusion in the crystal of a cation, for example, a proton, an alkali metal or an alkaline earth metal cation. This can be expressed wherein the ratio of the Group 13 element (e.g., aluminum or boron) to the number of various cations, such as H+, Ca2+/2, Sr2+/2, Na+, K+, or Li+, is equal to unity.
Molecular sieves that find application in catalysis include any of the naturally occurring or synthetic crystalline molecular sieves. Examples of these molecular sieves include large pore zeolites, intermediate pore size zeolites, and small pore zeolites. These zeolites and their isotypes are described in “Atlas of Zeolite Framework Types”, eds. Ch. Baerlocher, L. B. McCusker, D. H. Olson, Elsevier, Sixth Revised Edition, 2007, which is hereby incorporated by reference. A large pore zeolite generally has a pore size of at least about 6.5 to 7 Å and includes LTL, MAZ, FAU, OFF, *BEA, and MOR framework type zeolites (IUPAC Commission of Zeolite Nomenclature). Examples of large pore zeolites include mazzite, offretite, zeolite L, zeolite Y, zeolite X, omega, and beta. An intermediate pore size zeolite generally has a pore size from about 4.5 Å to less than about 7 Å and includes, for example, MFI, MEL, EUO, MTT, MFS, AEL, AFO, HEU, FER, MWW, and TON framework type zeolites (IUPAC Commission of Zeolite Nomenclature). Examples of intermediate pore size zeolites include ZSM-5, ZSM-11, ZSM-22, ZSM-57, MCM-22, silicalite 1, and silicalite 2. A small pore size zeolite has a pore size from about 3 Å to less than about 5.0 Å and includes, for example, AEI, CHA, ERI, KFI, LEV, SOD, and LTA framework type zeolites (IUPAC Commission of Zeolite Nomenclature). Examples of small pore zeolites include ZK-4, SAPO-34, SAPO-35, ZK-14, SAPO-42, ZK-21, ZK-22, ZK-5, ZK-20, zeolite A, chabazite, zeolite T, and ALPO-17.
Synthesis of molecular sieve materials typically involves the preparation of a synthesis mixture which comprises sources of all the elements present in the molecular sieve often with a source of hydroxide ion to adjust the pH. In many cases a structure directing agent is also present. Structure directing agents are compounds which are believed to promote the formation of molecular sieves and which are thought to act as templates around which certain molecular sieve structures can form and which thereby promote the formation of the desired molecular sieve. Various compounds have been used as structure directing agents, including various types of quaternary ammonium cations. However, there remains a need for new structure directing agents which offer the possibility of improving the synthesis of known molecular sieves or of allowing the synthesis of new molecular sieve materials.
The synthesis of molecular sieves is a complicated process. There are a number of variables that need to be controlled in order to optimize the synthesis in terms of purity, yield and quality of the molecular sieve produced. A particularly important variable is the choice of synthesis template (structure directing agent), which usually determines which framework type is obtained from the synthesis. This is mentioned, for example, in U.S. Pat. No. 4,310,440 (Wilson et al.), which teaches that “not all templating agents suitably employed in the preparation of certain species are suitable for the preparation of all members of the generic class.” It is also well known that the same template may induce the formation of different framework types. Accordingly, there is a need for new templates and new ways of making molecular sieves.